1. Field of the Invention
The present invention relates to a CFI-type zeolite containing fourteen-membered ring pores useful as a conversion catalyst for organic compounds, a process for the preparation of the zeolite, a catalyst prepared from the zeolite, and a process for the conversion of organic compounds.
2. Description of Related Arts
The CFI-type zeolite is a zeolite containing novel fourteen-membered ring pores invented by Yoshikawa and Devis and also is called CIT-5. Processes for the synthesis and the structure of the zeolite are already disclosed by the following literatures:                Literature 1: WO99/08961        Literature 2: Chemical Communications, 2179 (1997)        Literature 3: Journal of Physical Chemistry, B, 102, 7139 (1998)        Literature 4: Journal of Catalysis, 182, 463 (1999)        Literature 5: Shokubai, 41, 380 (1999)        
Literature 2 describes CIT-5 having a SiO2/Al2O3 ratio of 50, but no physical shape thereof. Furthermore, the CIT-5 having a SiO2/Al2O3 ratio of 50 could not be prepared according to the process as described therein. As described in Example 5 of literature 1, hydrothermal treatment of the reaction mixture having a known composition (LiOH/SiO2=0.1 and methylsparteinium hydroxide/SiO2=0.2) only produces a mixture containing amorphous materials without forming a finely crystallized CFI-type zeolite from the reaction mixture having a SiO2/Al2O3 ratio of 100. The other literatures describe no CIT-5 having a SiO2/Al2O3 ratio lower than 100, and also no CIT-5 having an atomic ratio of silicon to a heteroatom that is 45 or less. In literature 1, the synthesis of CIT-5 is carried out by use of the reaction mixture having a Si/Zn ratio of 25, but it is not clear whether zinc is contained in the resulting zeolite.
The CFI-type zeolite (CIT-5) contains a fourteen-membered ring pore which is large of the pore sizes of zeolites, and is expected as a novel material for catalysts. However, the related art has been unable to introduce a number of heteroatoms into the framework of the zeolite, that is, producing only CIT-5 having a small number of catalytic active sites. CIT-5 has a monodimensional pore of fourteen-membered ring size. The monodimensional pore is inferior in diffusion to multi-dimensional pores, and therefore smaller crystals are useful as catalysts. However, the related art has been unable to prepare CIT-5 having a number of active sites and furthermore small crystal size.